Studies of Mu-tong, Akebiae Caulis (2)¹⁾
Outer and inner morphologies of woody stems of Akebia plants growing in Japan and the botanical origin of Mokutsu produced in Japan

Abstract

The Japanese Pharmacopoeia Fifteenth Edition prescribes Akebiae Caulis, Mokutsu in Japanese, should be the woody stem of Akebia quinata Decaisne and A. trifoliata Koidzumi of the family Lardizabalaceae. We examined morphologically the woody stems of 3 wild Akebia taxa growing in Japan, A. quinata, A. trifoliata, and A. × pentaphylla Makino, for the purpose of finding morphological criteria to discriminate them and for identifying Mokutsu in the market. We found that the 3 taxa could be distinguished by a combination of surface color of stem, inner morphologies of stone cells and sclerenchyma cells, etc. with an accuracy of more than 90%, though it had been reported that A. quinata and A. trifoliata could not be distinguished by only stem anatomy. Using these criteria, we found that the woody stems of all 3 Akebia taxa were circulated equally in the Japanese market. This is the first record that the stem of A. × pentaphylla is circulating in the market as Mokutsu.